A variety of decorative building shutters are available for installation adjacent to openings in buildings, such as windows. Such shutters are constructed from various materials, including wood, metal, and polymeric materials such as styrene and polypropylene.
Many of the shutters currently available are constructed as pre-sized integral units. One difficulty with such integral unit shutters is that many building openings, such as windows, are not always standard or uniform sizes. Therefore, integral, unitary shutters often do not match the requirements of a particular window or opening.
Shutters are available which are assembled from modular components in a range of sizes. Therefore, such modular shutters are easily tailored for particular installations.
Examples of such modular shutters are disclosed in U.S. Pat. No. 4,251,966 to Foltman, entitled "Adjustable Height Shutter", U.S. Pat. No. 5,152,166 to MacGowan, entitled "Modular Shutter Assembly", and U.S. Pat. No. 5,265,391 to Ricard et al., entitled "Stabilized Modular Shutter", all of which patents are assigned to the assignee of this application. Other examples of modular shutters are disclosed in U.S. Pat. No. 4,765,110 to MacLeod, entitled "Adjustable Plastic Shutter" and U.S. Pat. No. 5,060,442 to Chubb, entitled "Louvered Plastic Building Product."
Typically, modular shutters have a pair of side rails, a central shutter panel which, for example, may be planar or louvered, and top and bottom end rails. Generally, the side rails are cut to meet the particular size requirements of the shutter installation. The shutter panels are cut or sized accordingly. The width of modular shutters can be adjusted by use of shutter panels, end rails and mullions of different dimensions.
In some configurations, one or more central rails or mullions may be disposed between multiple shutter panels in the central portion of the shutter. Mullions may be used to provide additional rigidity to the shutter structure, and to alter the appearance of the shutter assembly.
Typically, the components of many existing modular shutters are molded and/or extruded from a plastic such as styrene or polypropylene. Styrene is a relatively rigid, easily molded and extruded material. Polypropylene is less rigid than styrene, but is also relatively easily molded and extruded.
Styrene shutters can be painted after they are assembled. Polypropylene shutters, on the other hand, can be molded or extruded in various colors to eliminate the subsequent step of painting.
In many existing modular shutters, each shutter panel has a pair of runners extending along the opposite sides of the panel, transverse to the plane of the shutter panel. Typically, each of the side rails of such modular shutters has a channel formed on the inner wall thereof to slidably receive the runners of the shutter panel.
In the aforementioned Foltman patent, the shutter panel runner is received in a flat, planar track formed on the inner wall of the side rail by a rear hook portion and a front generally flat lip.
Another example of a shutter having a flat, planar track to engage the shutter panel runner is shown in the aforementioned patent to MacLeod. The shutter disclosed in the MacLeod patent has a side rail track which includes two hook portions, one on the front of the side rail and one on the rear of the side rail.
Problems have been observed during assembly of such shutters, particularly shutters formed of polypropylene, due to the relative flexibility of the material. The runners of the shutter panel tend to disengage from the channel or track portions of the side rails when the shutter components are flexed, (i.e., bent concave or convex relative to the front of the shutter) to any appreciable extent.
In the existing shutters, such as those disclosed in the Foltman and MacLeod patents, only the front and rear edges of the runners are engaged by the tracks or channels formed on the side rails. These locations appear to be the positions of maximum deflection and distortion. Such distortion may allow the forward or back edge of the runners on the shutter panels, the mullions, and/or the end rails to escape from the track to permit separation of these components from the assembly.
Furthermore, the effectiveness of restraints provided at the front and back extremities of the various channel and track configurations on the side rails of existing shutter assemblies to retain the runners of the other components is often less than desired. This appears to be not only because of the location of the restraints (at positions of maximum deflection), but also because the limited interaction between runners and the tracks does not effectively prevent undesired separation thereof during assembly.
Disengagement of the runners from the side rails makes assembly of the shutters difficult, and tends to increase assembly time and cost thereof.
It would be desirable, therefore, to provide a shutter having the advantages of a modular design, while incorporating a shutter panel to side rail engagement configuration that would provide improved resistance to disengagement of the shutter panels and other components from the side rails during assembly.